Sterilizers and autoclaves are generally used in hospitals, industrial laboratories and other facilities for the purpose of sterilizing various solid, porous and liquid articles. Typically, the sterilizer or autoclave chamber is located in a wall between a controlled environment room such as a laboratory or an operating room and an adjacent room wherein the strict environmental controls and parameters are not maintained.
Vertically sliding doors are typically used in connection with such machines because they require a minimum of space in relation to the size of the opening they provide and they do not interfere with the loading and unloading of the machine. Such vertical sliding doors typically lower to open the autoclave and raise to a closed position.
Often, autoclave doors are electrically powered, with a switch-actuated motor drive system being used to raise and lower the door. Such powered doors pose a potential safety risk to autoclave operators in the event that the door is activated while the user's arms obstruct the path of the door. Such accidental activation may also damage articles being inserted or removed from the autoclave.
In order to avoid such damage or injury in the event of door obstructions, expensive and elaborate systems have previously been employed. Some prior systems employ expensive electrical sensing systems which detect door obstructions and generate a signal directing the motor to stop or perhaps reverse door motion, thus protecting the user and the sterilized articles. However, such systems are not entirely fail-safe. Sensors require optimal placement in order to detect obstructions. Also, the sensors must be adequately protected against the adverse conditions of the hot, humid sterilizer environment. Further, the sensor must satisfactorily be able to communicate with the circuitry driving the door motor. In view of these considerations, such obstruction sensing systems do not offer optimal fail-safes for user protection.
Obstructions to the autoclave door also have the potential to damage the motor drive system. Obstructing a door's motion prior to its limit of travel causes the motor to experience a dead-end load resulting in high stall torques that could produce damage or failure in the motor and the other drive components. A similar situation may result if an impatient operator attempts to manually actuate the powered door with an excessive force while the door is moving or stationary. This situation creates high induced loads within the motor and drive components that could also result in damage or failure. Such problems may also inadvertently arise during a power failure, e.g. in the wake of an electrical storm. With a prior system, a door may not be opened during a power failure without producing the same damage to the drive components.
In order to guard against such system damage, it has been necessary in the prior art to design the respective components to withstand such forces, or else incorporate expensive slip clutches or other such safeguards. Slip clutches require precision machining or adjustments in order to insure proper shaft alignments. Thus, expensive and elaborate arrangements must be provided in order to protect the motor parts either from obstructions or opening with excessive force.
Manual sterilizer doors have been conventionally opened with a door mounted handle for hand opening. Similarly, for powered doors, it is also known to have a power actuation switch generally mounted within arms reach for hand actuation. However, it is typical for operators to approach an autoclave unit carrying a load to be sterilized. In order to gain entry into the autoclave, the load must either be set down or held precariously in one hand while opening the door, creating inconvenience or even potential danger to the operator. Similar difficulties arise while removing the load. It would be desirable to minimize any inconvenience or danger to the operator.
In prior systems, it has been known to use mechanical securements such as detents and laches for securing autoclave doors. Such securements can be complicated and require precise alignment in order to function as desired. Also, such securements are susceptible to damage. it would be desirable to provide a securement that does not suffer from such drawbacks.
Additionally, in prior autoclaves, different mechanical structures are used for manually-opened doors than for powered doors. Due to these differences in hardware, it has been difficult to retrofit a manual door to include powered components.